The present invention relates to a spark ignition device having a plurality of discharging gaps for igniting a mixture of air and fuel such as combustible gas or gasoline in a combustion chamber of an internal combustion engine and to an in-cylinder direct fuel injection/spark ignition type internal combustion engine using the spark ignition device.
It is known that, in order to realize both reduction in an exhaust gas (particularly, reduction in NOx in a gasoline-fuel car) and improvement in fuel efficiency, combustion speed of a mixture (of air and fuel such as combustible gas or gasoline) in a combustion chamber has to be increased (this point will be described in detail in the beginning of “Detailed description of the invention”).
Japanese Patent Laid-Open No. H7(1995)-12037 discloses a spark ignition device in which an annular-shaped electrode distributing section made of a ceramic is provided along a side wall of a cylinder in an upper part of a combustion chamber (which corresponds to a cylinder in this specification) of an engine and three or more electrodes are provided at predetermined intervals in the inner surface of the annular-shaped electrode distributing section.